Personal Protective EquipmentBest Practices for Arc Exposures and Use of FR
Clothing

Courtesy of the Center to Protect Workers' Rights

Try to eliminate any potential arc-related injuries. When workers can be
exposed to electrical arcs, the first effort should be to eliminate the exposure
through engineering design. If eliminating all arc-related exposures is not
possible, try to limit the extent of such exposures through administrative
controls, including work practices (for example, reducing the available fault
current or using work techniques that will put more distance between the
worker and the point of the potential arc). (See Factors Affecting Heat
Exposure.)

Grease, oil, solvents, or other flammable substances. FR clothing that becomes
contaminated with grease, oil, solvents, or other flammable substances should
not be used because such contamination greatly reduces the effectiveness of the
clothing material. As with any PPE that becomes damaged, damaged FR clothing
must be replaced before resuming work that requires its use. Contaminated FR
clothing must be thoroughly cleaned, if possible, or replaced. See ASTM
F1449-01, Standard Guide for the Care and Maintenance of Flame, Thermally and
Arc Resistant Clothing.

Damaged FR clothing. FR clothing must be cared for as instructed by the
manufacturer. Clothing that is damaged (for example, torn) often requires
special repair techniques. For example, using common nylon thread may reduce
the value of the clothing's FR protection.

Use FR clothing that is rated for particular heat exposures. The FR clothing
industry has developed a heat energy rating system for FR fabrics. To identify
the appropriate FR clothing to use, the heat energy, measured in calories per
square centimeter (cal/cm2), to which workers are exposed needs to be
calculated. Guidance for calculating an arc's heat energy can be found in
numerous sources, including Section 130.7(c) and Appendix D of NFPA 70E.
Different methods (for example, software packages, mathematical formula) for
calculating heat energy are available. Employers need to make their best
estimates based on currently available information. Appendix D of NFPA 70E provides a detailed sample calculation of a flash protection boundary (NFPA 70E, Standard for Electrical Safety in the Workplace, 2004 Edition, National Fire
Protection Association). For other methods of estimating incident energy from an
electric arc, see OSHA's proposed revision of its electric power generation,
transmission, and distribution standards. [See Electric Power Generation, Transmission and Distribution; Personal Protective
Equipment. OSHA Federal Register Proposed Rule 70:34821-34980, (2005, June
15). Also available as a 2 MB PDF, 160 pages. See Appendix F to Section 1910.269—Clothing, on page
34940 (page 120 of the PDF version]